Introduction
There are about 100 known Erebia species, distributed variously across temperate regions of the northern hemisphere. Almost all species inhabit damp high altitude grasslands although a few occur down to sea level. Most species are dark brown and feature a series of white-centred black ocelli set within a suffused area of orange on the outer part of the wings. The markings are repeated on the underside but are more subdued. There are 14 species known from North America.
In North America the vast majority of Erebia species are restricted to Alaska or Canada, although many of them are also found in temperate Asia where the genus probably originated.
Erebia epipsodea is found in s.w. Alaska, Yukon, British Columbia, Alberta, Washington, Montana, Oregon, Idaho, Wyoming and Colorado.
Habitats
In common with most other Erebia species episodea is found in mountainous country, and is most often encountered as localised colonies in moist meadows and damp hollows dominated by fine grasses which thickly carpet the ground.
Lifecycle
The lifecycle is unknown. The majority of Erebia species lay their eggs singly at the base of blades of grasses or sedges. Females of epipsodea are often seen flying around Poa fendleriana and this is assumed to be the foodplant. Erebia larvae normally enter hibernation in the 2nd instar and spend the winter deep at the base of grasses, and may be buried under snow for several months. In the spring, after the snows melt, they awaken and resume feeding, becoming fully grown by early May. They feed nocturnally, high up on the grass blades, leaving nibbled notches which give away their presence. In poor spring seasons larval development may be very slow, and it is likely that some of the larvae are unable to complete their growth in a single season, and may spend 2 successive winters in hibernation. Erebia pupae are usually formed within a very flimsy cocoon at the base of grass tussocks.
Adult behaviour
Common Alpines have a very weak fluttering flight just above the grasses. Males imbibe moisture from damp ground. They patrol back and forth while the sun shines, dipping down at intervals into the grasses to investigate any dark object that could potentially be a female. Both sexes nectar at a wide variety of flowers, and occasionally bask on grass blades or on bare ground.